A Numerical Study on the Sensitivity of the Discrete Element Method: The Multi Particle Perspective

Based on the time-driven Discrete Element Method, granular flow within a hopper is investigated. Contacts are assumed as linear viscoelastic in normal and frictional-elastic in tangential direction. The hopper geometry is chosen according to Yang and Hsiau [1] who performed both experimental and numerical investigations. The considered setup is attractive, because it involves only a small number of particles enabling fast modeling. However, results on the experimental flow rates reported are contradictory and are afflicted with errors. By a visual analysis of the hopper fill levels at different points of time the correct average discharge times and flow rates are obtained. Own simulation results are in good agreement with the experimental flow rates and discharge times determined. Based on the thereby defined set of simulation parameters, a sensitivity analysis of parameters like friction coefficients, stiffnesses and time steps is performed. As flow properties, besides the overall discharge times, the time averaged axial and radial velocity distributions within the hopper are considered. Results show a strong connection of the friction coefficients with the discharge times and the velocity distributions. Other parameters only reveal a weak often indifferent influence on the studied flow properties.